This invention relates to air conveyor systems employing air jets to convey articles along a conveyor pathway.
An air conveyor is used for rapidly transporting plastic bottles or other lightweight articles between work stations as, for example, between a storage station and a bottle-filling station. A typical air conveyor includes a pair of parallel flanges spaced to define an elongate slot and a series of air jets on opposite sides of the slot. Plastic bottles are formed with annular rims adjacent the tops of their necks. With the bottle necks extending through the slot and the rims overlying the spaced flanges, the bottles are suspended from the flanges and hang below the slot. Pressurized air from the air jets is directed in streams toward the bottles. The bottles move through the slot because of the force of the air streams against the lightweight bottles.
Generally, to feed bottles into the conveyor slot, the bottles are placed on a top surface of an endless belt conveyor which conveys the bottles to an inlet end of the conveyor slot. The belt conveyor is positioned so that the necks and rims of the bottles align with the inlet end of the conveyor slot. To assist in alignment of the bottle neck and rims with the air conveyor slot as they are transported by the belt conveyor toward the input to the air conveyor slot, the air conveyor is typically provided with a pair of laterally spaced guide plates that project horizontally from the opposite sides of the air conveyor slot toward the belt conveyor and the approaching line of bottles. The guide plates have mutually opposed edges that are aligned with the opposed edges of the air conveyor flanges where the guide plates attach to the air conveyor, and diverge away from each other as the guide plates extend from the air conveyor and toward the approached stream of bottles on the belt conveyor. As the bottles are conveyed by the belt conveyor toward the air conveyor slot, their necks pass between the guide plate edges with their annular neck rings positioned just above the horizontally position guide plates. As the bottles are moved closer to the air conveyor slot, the opposed guide plate edges merge toward each other and at least one of the guide plate edges engages with the neck of any misaligned bottle and causes that bottle to move toward the center of the conveyor belt, thus aligning the misaligned bottle with the air conveyor slot.
There are two conditions that can occur that would cause a bottle being conveyed by the belt conveyor to the air conveyor input slot to fall rearwardly on the belt conveyor and thereby possibly contact other bottles on the belt conveyor causing them to fall. As a bottle is conveyed on the belt conveyor toward the air conveyor input slot, when the neck of the bottle comes into contact with one of the two guide plates, the friction from the contact between the guide plate and the bottle being moved by the belt conveyor toward the air conveyor input slot may cause the guide plate to push the bottle rearwardly on the belt, thus causing it to fall rearwardly. This has a tendency to occur as the bottle conveyed on the belt conveyor gets closer to the input of the air conveyor slot because the drag or friction force of the guide plate tending to push the bottle rearwardly will increase as the bottle is continued to be moved forwardly toward the air conveyor input slot after first making contact with the guide plate edge. Also, when the bottle is first conveyed into the air conveyor input slot by the belt conveyor, the air flow from only a few, for example the first pair of air jet heads on opposite sides of the air conveyor slot, will act against the bottle edging it to move downstream along the air conveyor slot. Only after the bottle is moved a short distance into the air conveyor slot does the air flow of more of the air jet heads act on the bottle causing it to be conveyed downstream through the air conveyor slot. When a bottle first enters the air conveyor input slot from the belt conveyor, because usually only the air flow from the first pair of air jet heads on opposite sides of the air conveyor slot acts on the bottle, at times the bottles will have a tendency to stop at the input to the air conveyor or move very slowly in the downstream direction to the air conveyor. This may result with a succeeding bottle conveyed by the belt conveyor coming into contact with the preceding bottle which at times results in the succeeding bottle being knocked rearwardly on the belt conveyor. The rearward falling of the succeeding bottle at times contacts other bottles on the belt conveyor causing them also to fall.
What is needed to overcome this problem is a device that causes bottles being transferred from the belt conveyor to the input of the air conveyor slot to quickly move into the air conveyor slot to a position sufficiently downstream in the air conveyor slot where the air flow from several of the air jet heads of the air conveyor will contact the bottle and move it downstream through the air conveyor.